External bone fixation struts and systems

ABSTRACT

The present application provides external bone fixation systems. The systems include one or more pairs of bone fixation platforms in the form of rings or partial rings. The platforms may be coupled to corresponding bone segments. The pair of platforms are configured to accept a plurality of struts extending therebetween. The struts are configured to attach to the platforms via joints that provide three degrees of rotation. The struts are also configured such that their longitudinal length extending between the joints/platforms can be incrementally adjusted while attached to the platforms. The struts are further configured such that their total range of length adjustment can be increased by coupling at least one add-on component to the struts in situ. The lengths of each of the plurality of struts may be adjusted to arrange the platforms, and thereby the bone segment coupled thereto, in particular relative positions and orientations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/247,289, filed Dec. 7, 2020, and entitled External Bone FixationSystems, which is a continuation of U.S. patent application Ser. No.16/059,733, filed Aug. 9, 2018, and entitled External Bone FixationSystems, which is a continuation of PCT Patent Application No.US/2017/017276, filed Feb. 10, 2017, and entitled External Bone FixationSystems, which claims priority benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 62/362,351, filed Jul. 14, 2016, andU.S. Provisional Patent Application No. 62/415,741, filed Nov. 1, 2016,the contents of which are hereby expressly incorporated herein byreference in their entireties.

FIELD OF THE INVENTION

The present disclosure is generally directed to external bone fixationsystems and related methods. More particularly, the present disclosureis directed to external bone fixation systems and related methods thatinclude a plurality of length-adjustable struts rotatably coupledbetween a pair of platforms configured to affix to bone segments.

BACKGROUND OF THE INVENTION

External fixation devices have been used to treat bone and tissueconditions by positioning bone or tissue segments in desired relativepositions based on particular clinical needs. One form of externalfixation devices is a hexapod fixation device. Hexapod devices, or moreformally called Stewart platforms, include six degree of freedom (6DOF)parallel manipulators or struts. Generally, these devices have theability to manipulate an article of interest relative to a base in allthree orthogonal axis translations (X, Y, Z position) and all rotationsabout those three orthogonal axes (roll, pitch, yaw pose).

When configured as bone or tissue fixation systems, hexapod systemstypically include a pair of rings that serve as bone fixation platforms.The platforms are typically connected with six struts that extendbetween the platforms. The struts and platforms are commonly connectedvia spherical or cardan joints that allow three rotations about threeorthogonal axes. While some of these struts allow for length adjustment,their minimum and/or maximum lengths may not meet the needs of aparticular clinical situation. For example, minimizing the distancebetween the platforms to a distance less than that afforded by aparticular strut requires the use of a shorter struts—which naturallylimits the adjustable range (i.e., the maximum length) of the struts.

As a result, current hexapod bone fixation systems utilize a collectionof struts of differing lengths (or differing length ranges) whichprovide “short” struts for use when the platforms need to be closetogether and “long” struts for use when the platforms need to be furtherapart. In many instances these struts must be progressively orregressively swapped for the next length strut during a bone or tissuecorrection process, which is both a time consuming and costly processgiven that the strut being replaced cannot be re-used. Furthercomplicating such systems is that some situations require a variety ofdiffering strut lengths. For example, a variety of differing strutlengths is commonly required when extreme initial angulations orrotations are present. The selection process of the correct combinationof differing strut lengths in such a situation is a time consumingprocess that is typically carried out by trial and error in an operatingroom. Such systems and situations thereby also require an excessiveamount of inventory, which is also costly and often confusing toproperly utilize.

Physically changing struts, aside from being a nuisance, also limits theavailable dynamic range of the system when attempting to reduce adeformity in an acute fashion. In this situation, struts are usually notadded until such an acute correction is accomplished leaving thereduction to be held by operation room staff while additional members ofthe operation room staff pick and choose which struts will fit betweenthe platforms at the prescribed locations. This process is timeconsuming and requires a large inventory.

Current hexapod fixation systems also typically utilize connectionsbetween the platforms and struts that require the use of one or morefasteners that need be tightened at the time of application. As such,connecting six struts at both ends to the platforms (i.e., twelveconnections), sometimes in a trial and error fashion, is a difficult andtime consuming task. Complicating matters is the fact that many currenthexapod fixation systems utilize loose fasteners which must be appliedusing instruments. These fasteners and instruments add to the collectionof parts and materials which must be kept track of in an operating roomsetting while the fixation system is employed, such as while a reductionis trying to be maintained.

Accordingly, hexapod fixation systems and related methods that provideincreased length adjustment ranges while remaining coupled to theplatforms, decrease the amount of associated inventory, can be installedrelatively quickly, and reduce costs are desirable.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure provides an external bone fixationsystem, comprising a first platform, a second platform and at least sixlength-adjustable strut assemblies. The first platform defines anopening and is configured to couple to a first bone segment. The secondplatform defines an opening and is configured to couple to a second bonesegment. Each of the strut assemblies include an externally threaded rodportion translatable through a strut body portion. The rod portion ofeach strut assembly is coupled to one of the first and second platformsvia a respective joint and the strut body portion of each strut assemblyis coupled to the other of the first and second platforms via arespective joint. The strut assemblies are coupled to the first andsecond platforms in pairs of strut assemblies spaced about the first andsecond platforms. The pairs of strut assemblies each include a firststrut assembly coupled to the respective platform via the joint of thethreaded rod portion thereof and a second strut assembly coupled to therespective platform via the joint of the strut body portion thereof.

In another aspect, the present disclosure provides an external bonefixation system including a first platform, a second platform and aplurality of length-adjustable strut assemblies. The first platform isconfigured to couple to a first bone segment and defining an opening.The second platform is configured to couple to a second bone segment anddefining an opening. The strut assemblies extend between the first andsecond platform within an operable range of angulation or orientationwith respect to the platforms. At least one of the rod portion and thebody portion of each strut assembly is configured to attach to one ofthe first platform and the second platform by engaging the respectiveplatform in a non-operable angulation or orientation with respectthereto and rotation of the strut assembly into the operable range ofangulation or orientation.

In another aspect, the present disclosure provides a strut assembly foran external bone fixation system. The strut assembly includes a strutbody, an externally threaded first rod portion and an externallythreaded add-on rod portion. The strut body portion includes a cavityextending therethrough and internal threads. The strut body alsoincludes a first joint at an end portion thereof configured to couple toa fixation platform. The first rod portion is translatable through thestrut body portion. The first rod portion includes a second joint at anend portion thereof configured to couple to a fixation platform. Theexternally threaded add-on rod portion is configured to attach to thefirst rod portion to extend the length thereof. The length between thefirst and second joints is adjustable. The add-on rod portion isattachable to the first rod portion when the first and second joints areeach coupled to a platform.

These and other objects, features and advantages of this disclosure willbecome apparent from the following detailed description of the variousaspects of the disclosure taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purposes of illustrating the external bone fixation systems andrelated methods described herein there is shown illustrativeembodiments. These illustrative embodiments are in no way limiting interms of the precise arrangement and operation of the disclosed externalfixation systems and other similar embodiments are envisioned.

FIG. 1 is a perspective view of an external bone fixation system in afirst configuration corresponding to a most compact configurationincluding a plurality of platforms and a plurality of interconnectedstrut assemblies.

FIG. 2 is a perspective view of the external bone fixation system ofFIG. 1 in a second configuration corresponding to an extendedconfiguration or state.

FIG. 3 is a perspective view of a strut assembly of the external bonefixation system of FIG. 1 shown in a most compact state.

FIG. 4 is a side view of a strut assembly of the external bone fixationsystem of FIG. 1 shown in an extended configuration or state.

FIG. 5 is a front view of the strut assembly of FIG. 4 .

FIG. 6 is a side cross-sectional view of the strut assembly of FIG. 4 asindicated in FIG. 5 .

FIG. 7 is a front cross-sectional view of the strut assembly of FIG. 4as indicated in FIG. 4 .

FIG. 8 is a cross-sectional view of the strut assembly of FIG. 4 asindicated in FIG. 4 .

FIG. 9 is a cross-sectional view of the strut assembly of FIG. 4 asindicated in FIG. 4 .

FIG. 10 is a cross-sectional view of the strut assembly of FIG. 4 asindicated in FIG.

FIG. 11 is an exploded view of a release mechanism of a strut body of astrut assembly of the external bone fixation system of FIG. 1 .

FIG. 12 is an exploded view of a pre-installed rod portion, a connectionelement and an add-on rod portion.

FIGS. 13-17 illustrate the connection element progressively coupling thepre-installed rod portion and the add-on rod portion of FIG. 12 .

FIG. 18 is a detailed view of the timing geometry for the pre-installedrod portion and the add-on rod portion of FIG. 12 .

FIG. 19 is an exploded view of a joint mechanism of a strut body of astrut assembly of the external bone fixation system of FIG. 1 .

FIG. 20 illustrates perspective views of a platform of a strut assemblyof the external bone fixation system of FIG. 1 .

FIG. 21 is a perspective view of a strut assembly aligned with a stud ofa platform in a non-operable orientation.

FIG. 22 is a perspective view of the strut assembly engaged with thestrut of the platform in the non-operable orientation of FIG. 21 .

FIG. 23 is perspective view of the strut assembly coupled to the strutof the platform of FIG. 21 by rotation of the strut in to an operableorientation.

FIG. 24 is an exploded view of a joint mechanism of a threaded rodportion of a strut assembly of the external bone fixation system of FIG.1 .

FIG. 25 is a perspective view of exemplary interconnected strutassemblies of another exemplary external bone fixation system in a firstconfiguration according to the present disclosure.

FIG. 26 is a side view of the interconnected strut assemblies of FIG. 25.

FIG. 27 is a top view of the interconnected strut assemblies of FIG. 25.

FIG. 28 is a perspective view of the interconnected strut assemblies ofFIG. 25 in a second configuration.

FIG. 29 is a top view of the interconnected strut assemblies of FIG. 25in the second configuration.

FIG. 30 is a side view of the interconnected strut assemblies of FIG. 25in the second configuration.

FIG. 31 is a perspective view of the interconnected strut assemblies ofFIG. 25 in a collapsed third configuration and coupled to platforms ofthe external bone fixation system.

FIG. 32 is a top view of the external bone fixation system of FIG. 31 .

FIG. 33 is a side view of the external bone fixation system of FIG. 31 .

FIG. 34 is a bottom perspective view of the external bone fixationsystem of FIG. 31 in an extended configuration of the interconnectedstrut assemblies.

FIG. 35 is an elevational perspective view of the external bone fixationsystem of FIG. 33 .

FIG. 36 is a side view of the external bone fixation system of FIG. 33 .

FIG. 37 is a perspective view of the interconnected strut assemblies ofFIG. 25 in the third configuration and the platforms of the externalbone fixation system.

FIG. 38 is a perspective view of the interconnected strut assemblies ofFIG. 25 in the extended configuration and the platforms of the externalbone fixation system.

FIG. 39 is a perspective view of the interconnected strut assemblies ofFIG. 25 in the extended configuration and connected the platforms of theexternal bone fixation system.

FIG. 40 illustrates bottom perspective and side view of theinterconnected strut assemblies of FIG. 25 in the collapsed thirdconfiguration and connected the platforms of the external bone fixationsystem.

FIG. 41 illustrates bottom perspective and side view of theinterconnected strut assemblies of FIG. 25 in the collapsed thirdconfiguration with add-on rods installed and connected the platforms ofthe external bone fixation system.

FIG. 42 is a top perspective view of a strut-platform connectionmechanism coupling a pair of strut assemblies of the external bonefixation system of FIG. 25 .

FIG. 43 is a bottom perspective view of the strut-platform connectionmechanism of FIG. 42 .

FIG. 44 is a top perspective view of the strut-platform connectionmechanism of FIG. 42 coupling the pair of strut assemblies to aplatform.

FIG. 45 is a bottom perspective view of the strut-platform connectionmechanism of FIG. 42 coupling the pair of strut assemblies to aplatform.

FIG. 46 is a top view of a platform of the external bone fixation systemof FIG. 25 .

FIG. 47 is an exploded perspective view of an exemplary strut assemblyof the external bone fixation system of FIG. 25 .

FIG. 48 is an exploded perspective view of an exemplary lengthadjustment mechanism of a strut assembly of the external bone fixationsystem of FIG. 25 .

FIG. 49 is an exploded perspective view of an exemplary lengthadjustment mechanism of a strut assembly of the external bone fixationsystem of FIG. 25 .

FIG. 50 is a perspective view of an exemplary partially-threaded nut ofthe length adjustment mechanism of FIG. 48 .

FIG. 51 is a side view of the partially-threaded nut of FIG. 50 .

FIG. 52 is a cross-sectional view of the partially-threaded nut of FIG.50 .

FIG. 53 is a perspective view of the exemplary length adjustmentmechanism of FIG. 48 .

FIG. 54 is a cross-sectional side view t of he exemplary lengthadjustment mechanism of FIG. 48 in an activated state.

FIG. 55 is a cross-sectional side view of the exemplary lengthadjustment mechanism of FIG. 48 in a deactivated state.

FIG. 56 is a cross-sectional perspective view of the exemplary lengthadjustment mechanism of FIG. 48 in an activated state.

FIG. 57 is a cross-sectional perspective view of the exemplary lengthadjustment mechanism of FIG. 48 in a deactivated state.

FIG. 58 is an exploded perspective view of the of exemplary lengthadjustment mechanism of FIG. 48 .

FIG. 59 is a perspective view of exemplary interconnected strutassemblies of another exemplary external bone fixation system accordingto the present disclosure.

FIG. 60 is a top view of the interconnected strut assemblies of FIG. 59.

FIG. 61 is an elevational perspective view of the interconnected strutassemblies of FIG. 59 .

FIG. 62 is a bottom perspective view of the interconnected strutassemblies of FIG. 59 .

FIG. 63 is an elevational perspective view of the interconnected strutassemblies of FIG. 59 .

FIG. 64 is a side view of the external bone fixation system of FIG. 59with the interconnected strut assemblies coupled to a plurality ofplatforms.

FIG. 65 is an elevational perspective view of the external bone fixationsystem of FIG. 59 with bone segments illustrated.

FIG. 66 is an elevational perspective view of the external bone fixationsystem of FIG. 59 illustrating a connection mechanism coupling a pair ofstrut assemblies to a platform.

FIG. 67 is a bottom perspective view of the external bone fixationsystem of FIG. 59 illustrating a connection mechanism coupling a pair ofstrut assemblies to a platform.

FIG. 68 is an elevational perspective view of the external bone fixationsystem of FIG. 59 illustrating a connection mechanism coupling a pair ofstrut assemblies to a pair of platforms.

FIG. 69 is a perspective view of the external bone fixation system ofFIG. 59 illustrating strut-platform connection mechanisms.

FIG. 70 is a side view of the external bone fixation system of FIG. 59illustrating strut-platform connection mechanisms.

FIG. 71 is a perspective view of exemplary length adjustment mechanismsof strut assemblies of the external bone fixation system of FIG. 59 .

FIG. 72 is a side view of the length adjustment mechanisms of FIG. 71 .

FIG. 73 is a cross-sectional view of the length adjustment mechanisms ofFIG. 71 .

FIG. 74 is another cross-sectional view of the length adjustmentmechanisms of FIG. 71 .

FIG. 75 is another cross-sectional view of the length adjustmentmechanisms of FIG. 71 .

FIG. 76 is another cross-sectional view of the length adjustmentmechanisms of FIG. 71 .

FIG. 77 is a perspective exploded view of the length adjustmentmechanisms of FIG. 71 .

FIG. 78 is another perspective exploded view of the length adjustmentmechanisms of FIG. 71 .

FIG. 79 is a side exploded view of the length adjustment mechanisms ofFIG. 71 .

FIG. 80 is another side exploded view of the length adjustmentmechanisms of FIG. 71 .

FIG. 81 is another cross-sectional view of the length adjustmentmechanisms of FIG. 71 .

FIG. 82 is a perspective view of another exemplary external bonefixation system according to the present disclosure.

FIG. 83 is an exterior elevational perspective view of a strut-platformconnection mechanism of the external bone fixation system of FIG. 82coupling a pair of strut assemblies to a platform.

FIG. 84 is an exterior bottom perspective view of the strut-platformconnection mechanism of FIG. 83 .

FIG. 85 is an interior elevational perspective view of thestrut-platform connection mechanism of FIG. 83 .

FIG. 86 is top view of a platform of the external bone fixation systemof FIG. 82 .

FIG. 87 is an elevational perspective view of the platform of FIG. 86 .

FIG. 88 is an enlarged elevational perspective view of the platform ofFIG. 86 .

FIG. 89 is a side perspective view of the platform of FIG. 86 .

FIG. 90 is an exterior bottom perspective view of the strut-platformconnection mechanism of FIG. 83 couple to the platform of FIG. 86 .

FIG. 91 is a top view of the strut-platform connection mechanism of FIG.90 .

FIG. 92 is a side view of the strut-platform connection mechanism ofFIG. 90 .

FIG. 93 is a cross-sectional view of the strut-platform connectionmechanism of FIG. 90 .

FIG. 94 is a perspective view of the strut-platform connection mechanismof FIG. 83 .

FIG. 95 is a side view of the strut-platform connection mechanism ofFIG. 94 .

FIG. 96 is a top view of the strut-platform connection mechanism of FIG.94 .

FIG. 97 is a cross-sectional view of the strut-platform connectionmechanism of FIG. 94 .

FIG. 98 is another cross-sectional view of the strut-platform connectionmechanism of FIG. 94 .

FIG. 99 is a perspective view of a connection mechanism mount of thestrut-platform connection mechanism of FIG. 83 .

FIG. 100 is a front view of the connection mechanism mount of FIG. 99 .

FIG. 101 is a side view of the connection mechanism mount of FIG. 99 .

FIG. 102 is a cross-sectional view of the connection mechanism mount ofFIG. 99 .

FIG. 103 is a top view of the connection mechanism mount of FIG. 99 .

FIG. 104 is another cross-sectional view of the connection mechanismmount of FIG. 99 .

FIG. 105 is another cross-sectional view of the connection mechanismmount of FIG. 99 .

DETAILED DESCRIPTION

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements. Anyexamples of parameters are not exclusive of other parameters of thedisclosed embodiments. Components, aspects, features, configurations,arrangements, uses and the like described, illustrated or otherwisedisclosed herein with respect to any particular embodiment may similarlybe applied to any other embodiment disclosed herein.

The present disclosure provides for six degree of freedom (6DOF) bone ortissue fixation systems and related fixation methods 100 as shown inFIGS. 1-18 which include the desirable stability and mobilitycharacteristics of a hexapod system without time consuming strut-lengthchoices and assembly difficulties. The fixation systems 100, as shown inFIGS. 1-18 , also include struts assemblies 110 with relatively largedynamic ranges such that acute reductions in the operating room are notlimited by the system 100 itself and the necessity of selecting andreplacing one or more of the struts 110 during the reduction process. Insome embodiments, the fixation systems and related fixation methods ofthe present disclosure 100 as shown in FIGS. 1-18 are particularlyadvantageous for the repair of fractures or deformities, such asfractures of or deformities in relatively long bones.

In one embodiment, the fixation systems or devices 100 include strutassemblies each formed of a threaded rod assembly 25 threadably coupledwithin a strut body 5. As explained further below, the threaded rodassembly 25 may include a first strut screw or rod 12 and, potentially,a second add-on strut screw or rod 13. The threaded rod assembly 25 mayinclude external threads, as shown in FIGS. 1-7, 10, 12 and 13 . As alsoshown in FIGS. 1-3 the threaded rod assembly 25 may include or define alongitudinal axis X-X, and may be elongate along the axis X-X. In someembodiments, the threaded rod assembly 25 may be cylindrical. Thethreaded rod assembly 25 may define a length L1 along the longitudinalaxis X-X which includes the external threads, as shown in FIG. 3 .

As shown in FIGS. 1-7 and 11 , the threaded rod assembly 25 may betranslatably received within the strut body 5. The strut body 5 maythereby include a non-threaded and potentially substantially smoothcavity configured to accept the strut body 5 therein/therethrough, suchas along the longitudinal axis X-X. The strut body 5, and potentiallythe cavity thereof, may define a length L2 along the longitudinal axisX-X that is less than the length L1 of the threaded rod assembly 25, asshown in FIG. 3 . The strut body 5 may be configured such that the strutbody 5 is free to extend and/or translate through the strut body 5, asshown in FIGS. 1, 3-7, 16 and 17 . As explained further below, one endportion of the strut body 5 may be coupled to a first platform 120, andan opposing end portion of the threaded rod assembly 25 may be coupledto a second platform 130. In this way, the strut body 5 and the threadedrod assembly 25 may translate with respect to each other along the axisX-X to provide a relatively large range of length adjustability to thestrut assembly 110 and, thereby the distance and/or orientation betweenthe first and second platforms 120, 130 as shown in FIGS. 1 and 2 .

As explained further below, the first and second platforms 120, 130 maybe rings or partial rings such that they extend, at least partially,about an opening and/or an axis X2-X2 (and, potentially, at leastpartially about bone and/or tissue in situ). The strut assemblies 110may be coupled to the first and second platforms 120, 130 about the axisX2-X2. For example, as shown in FIGS. 1 and 2 the strut assemblies 110may be positioned and coupled circumferentially to the first and secondplatforms 120, 130, and each strut assembly 110 may be attached to thefirst and second platforms 120, 130 at differing positions about theaxis X2-X2. As such, the strut assemblies 110 may be angled with respectto the axis X2-X2.

As shown in FIGS. 1 and 2 , the strut assemblies 110 may be arranged andcoupled with the first and second platforms 120, 130 in such aconfiguration that provides clearance for the extension of the threadedrod assembly 25 from the strut body 5 (or vice versa). For example, thestrut assemblies 110 may be coupled to the first and second platforms120, 130 in pairs of adjacent and relatively closely spaced joints, andsuch pairs of strut assemblies 110 may be spaced a relatively closelygreater distance apart about the first and second platforms 120, 130(and thereby about the axis X2-X2). Each pair of strut assemblies 110may include a joint coupling the threaded rod assembly 25 of one strutassembly 110 to the first or second platform 120, 130 and a jointcoupling the strut body 5 of the other strut assembly 110 to the firstor second platform 120, 130. The strut assemblies 110 are thereby joinedto the first and second platforms 120, 130 in an alternating pattern ororientation.

The strut assemblies 110 of each pair coupled to the first and secondplatforms 120, 130 may extend to the other platform 120, 130 at opposingangular directions about the axis X2-X2—one strut assembly 110 mayextend and couple to the other platform 120, 130 at a differingclockwise position and the other strut assembly 110 may extend andcouple to the other platform 120, 130 at a differing counter clockwiseposition.

As discussed above, the strut assemblies 110 may be configured such thatthe threaded rod assembly 25 is able to extend fully through the strutbody 5, such as shown in a distracted arrangement as shown in FIGS. 1and 3 . As each pair of strut assemblies 110 includes one joint couplingthe threaded rod assembly 25 of a first strut assembly 110 to therespective first or second platform 120, 130 and one joint coupling thestrut body 5 of a second strut assembly 110 to the respective first orsecond platform 120, 130, the threaded rod assembly 25 of the secondstrut assembly 110 is able to extend out from the strut body 5 (coupledto the respective first or second platform 120, 130) withoutinterference from the first strut assembly 110, as shown in FIG. 1 . Thealternating orientation of the strut assemblies 110 of the pairs ofstrut assemblies 110 coupled to the first and second platform 120, 130thereby allows the threaded rod assembly 25 to define a relatively longlength L1. In this way, the system 100 is able to provide an acutereduction of the distance between the first and second platform 120, 130(and the bone or tissue segments coupled thereto) as shown in FIG. 1 ,while still providing for adjustment to a relatively large distance(i.e., relatively large distraction) as shown in FIG. 2 . Thisrelatively large dynamic envelop of the adjustability of the first andsecond platforms 120, 130 is thereby provided without the need for thereplacement of or addition to the strut assemblies 110, which canadvantageously free up the surgeon to concentrate on the orthopediccondition and the reduction of the fracture or deformity.

As shown in FIGS. 3-7 and described above, the threaded rod assembly 25(i.e., the first strut screw or rod 12 and, potentially, the secondadd-on strut screw or rod 13) may be provided within an open cavity ofthe strut body 5 and threadably engage with corresponding internalthreads of the strut body 5. The strut assemblies 110 thereby from aprismatic joint (via the threaded rod assembly 25 and the strut body 5).In some embodiments, the strut body 5 of the strut assemblies 110 may bethreadably engaged with the threaded rod assembly 25 via at least onethreaded key 8, as shown in FIGS. 6, 7, 10 and 11 . The at least one key8 may include or form internal thread that corresponds to the externalthread of the threaded rod assembly 25. The strut assemblies 110 may beconfigured such that the at least one key 8 (such as two opposing keys8, 8) is able to be manually moved in and out in a radial fashion (e.g.,with respect to the axis X-X) to engage and disengage the threaded rodassembly 25.

As shown in FIG. 11 , the actuation of at least one threaded key 8 maybe accomplished via rotation (e.g., manual rotation, potentially aboutthe axis X-X) of an outer sleeve 6. The at least one threaded key 8maybe provided within at least one corresponding opening in the strutbody 5, and the outer sleeve 6 may be provided about the at least onethreaded key 8, the strut body 5 and the threaded rod assembly 25 via aneccentric bore. The eccentric bore may include a camming surface suchthat when the sleeve 6 is rotated (e.g., about the axis X-X), thecamming surface that either allows the at least one threaded key 8 tomove away from and out of engagement with the threaded rod assembly 25via a corresponding resilient member 10 or forces the at least onethreaded key 8 into engagement with the threaded rod assembly 25 (i.e.,the first strut screw 12 and/or the second add-on strut screw 13). Asalso shown in FIG. 11 , the strut assemblies 110 may also include atleast one radial pin 2 provided with a corresponding slot and the sleeve6 which thereby controls the positioning of the sleeve 6 relative to thestrut body 5. The at least one slot may include at least oneaxially-extending indentation corresponding to the positon of the atleast one pin 2 (and thereby the sleeve 6 itself) in which the at leastone threaded key 8 is forced into engagement with the threaded rodassembly 25 via the sleeve 6 and/or the positon of the at least one pin2 (and thereby the sleeve 6 itself) in which the at least one threadedkey 8 is forced out of engagement with the threaded rod assembly 25 viathe at least one spring 8. As shown in FIG. 11 , the strut assemblies110 may include a resilient member 9 configured to axially bias thesleeve 6 such that the at least one pin 2 is biased into the at leastone axially-extending indentation of the at least one slot.

Rotation of the threaded rod assembly 25 relative to the strut body 5,or rotation of the strut body 5 relative to the threaded rod assembly25, while the at least one threaded key 8 in engagement with thethreaded rod assembly 25 thereby results in a forced translation of thestrut body 5 relative to the threaded rod assembly 25 (or vice versa),thus lengthening or shortening the strut assembly 110. While the atleast one threaded key 8 is disengaged from the threaded rod assembly25, the threaded rod assembly 25 is free to move (axially along the axisX-X and rotationally about the axis X-X) within the strut body 5 suchthat the length of strut assembly 110 can be freely and quicklyadjusted.

While the at least one threaded key 8 and outer sleeve 6 of the strutbody 5 allows for selective length adjustment of the struts 110 (i.e.,the axial X-X length between the joint of the threaded rod assembly 25and the joint of the strut body 5, and thereby the distance andorientation between the first and second platforms 120, 130), the system100 may also provide for adjustment of the length (e.g., along the axisX-X) of the threaded rod assemblies 25 (and/or the strut bodies 5), andthereby the total adjustable range of the system 100. In someembodiments, the system 100 may provide for adjustment of the totalpotential length of the struts 110 (and/or the strut bodies 5) withoutdetaching/disconnecting the struts 110 from the platforms 120, 130, orotherwise interfering with the functioning of the struts 110 in situ.

As shown in FIGS. 12 and 13 , in some embodiments the system 100 mayprovide for selective lengthening of the threaded rod assemblies 25without detaching/disconnecting the struts 110 from the platforms 120,130 or otherwise interfering with the functioning of the struts 110 insitu. For example, the first strut screw 12 of the threaded rodassemblies 25 shown in FIGS. 1-11 has been lengthened by the secondadd-on strut screw or rod 13, as shown in FIG. 11 . The threaded rodassemblies 25 may be lengthened through the use of at least one add-onthreaded rod 13 that includes external threads substantially the same asthe external threads of the pre-existing component(s) of the threadedrod assemblies 25 (the first strut screw 12), and may otherwise besubstantially similar to the pre-existing component(s) of the threadedrod assemblies 25. For example, the at least one add-on threaded rod 13may include the same thread pitch as the external threads of the firststrut screw 12 of the threaded rod assemblies 25. The at least oneadd-on threaded rod 13 (and/or the pre-existing component of thethreaded rod assemblies 25 forming the free end thereof—such as thefirst strut screw 12) may include an end configuration that ensures theclocking of the respective thread pitches such that the composite pitchremains continuous across the joined rods.

The threaded rod assemblies 25 may be lengthened via the add-on threadedrod 13 via several methodologies. In one example (not shown), thethreaded rods of the threaded rod assemblies 25 may include a cap screwarranged concentrically and placed within a central channel of theadd-on threaded rod 13. The add-on threaded rod 13 can be configuredsuch that the cap screw extends out the end of the add-on threaded rod13, but the head of the cap screw is maintained or captured within thecavity. The existing first threaded rod 12 may include a concentrictaped hole to threadably couple with the exposed portion of the capscrew. To accept an additional add-on threaded rod 13 to furtherlengthen the threaded rod assemblies 25, the pre-installed add-onthreaded rod 13 may be configured to accept a threaded insert behind thecaptured cap screw within the cavity. The threaded insert may includethe concentric taped hole for accepting the cap screw of the next add-onthreaded rod 13. In such a manner, any number of add-on threaded rods 13may be added to the threaded rod assemblies 25 in situ.

As another example (not shown), a threaded turnbuckle may be utilized asa connecting element between the in situ or pre-installed threaded rod(e.g., the first threaded rod 12 of a previously installed add-onthreaded rod 13) and an add-on threaded rod 13. The threaded turnbucklebe configured to threadably engage with internal threads of centralchannels of the pre-installed threaded rod, such as the first threadedrod 12, and the add-on threaded rod 13. The turnbuckle may include afirst portion with right hand sense external threads and a secondportion with left hand sense external threads. The turnbuckle may alsoinclude a socket or another suitable driving feature incorporated intoone end configured for providing a means of torque transmission to theturnbuckle. In such an embodiment, the internal threads of the in situor pre-installed threaded rod can include a thread pitch whose sense wasthe same as the one on the opposite end of the driving feature of theturnbuckle, with the add-on threaded rod 13 having the same thread senseas the end of the turnbuckle having the driving feature. A drive elementcan be inserted down the central channel in the add-on threaded rod 13and engaged with the driving feature of the turnbuckle. The add-onthreaded rod 13, while on the shaft of the driving element and thedriving feature of the turnbuckle engaged with the drive element, can beplaced coaxial to the in situ or pre-installed threaded rod and theturnbuckle torqued to thread into both the in situ or pre-installedthreaded rod and the add-on threaded rod 13 at the same time. Threadclocking of the external threads of the in situ or pre-installedthreaded rod and the add-on threaded rod 13 may be achieved by interdigitation features at the mating ends of the in situ or pre-installedthreaded rod and the add-on threaded rod 13.

As another example, the system 100 may include a turnbuckle connectingelement 22 that provides or allows for some means of pre-assembly suchthat the add-on threaded rod 13 and the connecting element 22 does notneed to be separately handled during installation, as shown in FIGS. 11and 12 . Similar to the turnbuckle described above, the connectingelement 22 may be configured to threadably engage with internal threads58 of central channels of the pre-installed threaded rod, such as thefirst threaded rod 12, and the add-on threaded rod 13. The connectingelement 22 may include a first portion 60 with external threads of afirst pitch and a second portion 61 with external threads of a secondpitch that is different than the first pitch. For example, the firstpitch may be fine thread pitch and the second pitch may be a coarsethread pitch (or vice versa). While the pitch of the external threads ofthe first and second portions 60, 61 may differ, the sense of thethreads may be same. As such, the internal threads 58 of thepre-installed threaded rod 12 may include the first pitch or the secondpitch (and the corresponding thread sense) at least at a first endthereof, and the internal threads 58 of the add-on threaded rod 13 mayinclude the other of the first pitch or the second pitch (and thecorresponding thread sense) at least at a first end thereof.

The internal threads of the second end of the add-on threaded rod 13opposing the first end thereof may include the same thread pitch as thefirst end of the other of the first pitch or the second pitch. Thesecond end of the add-on threaded rod 13 may thereby allow for anadditional add-on threaded rod 13 to be installed to further lengthenthe threaded rod assemblies 25, and thereby the further increase therange of the threaded rod assemblies 25 in situ.

In some embodiments, the internal threads 58 of the pre-installedthreaded rod 12 may include a coarse thread pitch, and the internalthreads 58 of the add-on threaded rod 13 may include a fine thread pitch(or vice versa). In such embodiments, if the connecting element 22 istorqued a first rotational direction and correspondingly threadablyengaged with the internal threads 58 of the pre-installed threaded rod12 and the add-on threaded rod 13, the connecting element 22 wouldprogress out of the add-on rod 13 at a given rate as it rotated, whileit would progress into the pre-installed threaded rod 12 at a relativelyfaster rate—thus differentially bringing the add-on threaded rod 13 intocontact with the pre-installed threaded rod 12. The connecting element22 may include a socket or another suitable driving feature 62incorporated into one end configured for providing such torquetransmission to the connecting element 22 (via through the channel ofthe pre-installed threaded rod 12, for example).

In this way, the connecting element 22 may be utilized to couple theadd-on threaded rod 13 to the pre-installed threaded rod 12 withoutdisconnecting or otherwise interfering with the pre-installed threadedrod 12 (i.e., can be installed in situ). In some embodiments, theconnecting element 22 may be threaded into engagement with the add-onthreaded rod 13, and the add-on threaded rod 13 may include finerpitched internal threads than the pre-installed threaded rod 12 (or viceversa). As shown in FIG. 12 , the connecting element 22 may include anon-threaded region 63 between the first and second portions 60, 61. Thenon-threaded region 63 may allow for the finer pitch threaded portion 60or 61 of the connecting element 22 to initially be partiallyover-threaded into whichever of the add-on threaded rod 13 and thepre-installed threaded rod 12 includes the finer pitched internalthreads.

For example, FIGS. 13-17 being utilized to bring together and couple thefirst pre-installed threaded rod 12 and the second or add-on threadedrod 13. As noted above, although two threaded rods of an external bonefixation system are being utilized to illustrate one exemplary use ofthe connecting element 22, the connecting element 22 may be utilized tobring together (or space apart) and couple any two members or portions(whether part of an external bone fixation system or part of anotherorthopedic or non-orthopedic mechanism or system). Further, although theconnecting element 22 is depicted and described as having externalthreads 60, 61 and the first and second rod 12, 13 as having matinginternal threads, the connecting element 22 may have internal threadsand the members may have external threads.

As shown in FIGS. 13 and 14 , initially the second rod or member 13 andthe connecting element 22 may be threadably coupled via relatively finepitch threads and rotated or torqued together (e.g., via a tool) tothreadably engage the first rod or member 12 via relatively course pitchthreads. In such an embodiment, the non-threaded portion 63 of theconnecting element 22 may extend between the first and second rods ormembers 12, 13. As shown in FIG. 14 , the second rod or member 13 andthe connecting element 22 may be rotated together as a unit until thefirst and second rods or members 12, 13 meet such that relativelyrotation between the first and second rods or members 12, 13 isprevented. As shown in FIGS. 15 and 16 , the connecting element 22 maybe further rotated therefrom such that the connecting element 22 travelsaxially through the first and second rods or members 12, 13. However,due to the finer pitch of the threaded connection between the connectingelement 22 and the second rod or member 13 than the threaded connectionbetween the connecting element 22 and the first rod or member 12, theconnecting element 22 may travel slower or for a shorter distance as itis rotated through the second rod or member 13 than the first rod ormember 12, as shown in FIGS. 16 and 17 . In this way, the connectingelement 22 may draw the first and second rods or members 12, 13together, such as to an arrangement wherein the external threads of thefirst and second rods or members 12, 13 are aligned or are continuous.It is noted that the combination of the relatively fine pitch threadsand the relatively fine pitch threads of the connecting element 22 andthe second rod member 12 and the first rod or member 12, respectively,provides for extremely high axial accuracy or adjustment between thefirst and second rods or members 12, 13 that may not be able to achievedvia a single thread pitch due to physical restraints (i.e., a threadpitch equating to the difference in thread pitch between the fine andcourse thread pitches may not be realistically physically achievable).

The connecting element 22 may be provided or otherwise pre-installedwith the add-on threaded rod 13 before being coupled with thepre-installed threaded rod 12. To make the most efficient use of theengaged threads of the connecting element 22 within the add-on threadedrod 13, the add-on threaded rod 13 and/or the connecting element 22 maybe configured such that the add-on threaded rod 13 and the connectingelement 22 are rotated together as the connecting element 22 is threadedinto the pre-installed threaded rod 12.

As shown in FIG. 18 , at least the free end of the pre-installedthreaded rod 12 and the ends of the add-on threaded rod 13 may include akeying element 53 that ensures the correct timing between the externalthreads the pre-installed threaded rod 12 and the ends of the add-onthreaded rod 13. In use, the first portion 60 of the connecting element22 may be pre-installed within the channel of the add-on threaded rod13, and the second portion 61 of the connecting element 22 may therebyextend from the add-on threaded rod 13. The add-on threaded rod 13 andthe connecting element 22 may be torqued (e.g., rotated together as aunit) such that the second portion 61 of the connecting element 22threadably engages the internal threads of the cavity 28 of thepre-installed threaded rod 12, and thereby travel axially into thepre-installed threaded rod 12 and draw the add-on threaded rod 13 andthe pre-installed threaded rod 12 together. The keying elements 53 ofthe add-on threaded rod 13 and the pre-installed threaded rod 12 may beconfigured such that when mating faces thereof are within an optimaldistance of one another, the mating faces of the keying elements 53contact one another and prevent relative rotation between the add-onthreaded rod 13 and the pre-installed threaded rod 12, as shown in FIG.18 .

As also shown in FIG. 18 , in such an embodiment the keying elements 53of the add-on threaded rod 13 and the pre-installed threaded rod 12 mayinclude recesses 54 corresponding to the mating faces that allow forrelative axial translation between the add-on threaded rod 13 and thepre-installed threaded rod 12. In such a state, the driving feature 62of the connecting element 22 may be engaged via the channel of theadd-on threaded rod 13 and rotated such that the connecting element 22threadably translates through the cavities of the add-on threaded rod 13and the pre-installed threaded rod 12 at different rates to therebyaxial translate the add-on threaded rod 13 and the pre-installedthreaded rod 12 towards one another. The connecting element 22 may betorqued until mating end faces 56 of the add-on threaded rod 13 and thepre-installed threaded rod 12 contact each other, as shown in FIG. 18 .The add-on threaded rod 13 and the pre-installed threaded rod 12 may beconfigured such that when the mating end faces 56 of the key elements 53of the add-on threaded rod 13 and the pre-installed threaded rod 12 areengaged, the add-on threaded rod 13 and the pre-installed threaded rod12 are securely or rigidly coupled and the pitch of the external threadsthereof are properly clocked, as shown in FIG. 18 .

The free end of the pre-installed threaded rod 12 or the free end ofadd-on threaded rod 13, if installed, may include a guide bushing 14configured to mate with the keying elements 53, mating end faces 56and/or recesses thereof, as shown in FIGS. 12-17 . The guide bushing 14may act to provide a relatively smooth surface for contact with theinterior of the cavity of the strut body 5, and thereby protect theexternal threads thereof. As also shown in FIG. 12 , a cap screw 3 maybe utilized to secure the guide bushing 14 to the pre-installed threadedrod 12 or the free end of add-on threaded rod 13 if installed.

Although the connecting elements 22 are described and utilized abovewith respect to a first pre-installed threaded rod 12 and a secondadd-on threaded rod 13 of a strut assembly, it is specifically andparticularly contemplated herein that the connecting elements 22 may beutilized with any other first and second members. In some embodiments,the first and second members coupled and brought together via aconnecting element 22 may not be associated with a strut assembly, nor a6 DOF bone or tissue fixation system. Stated differently, the first andsecond members coupled and brought together via a connecting element 22may be any first and second members configured to couple via theconnecting element 22. For example, the connecting element 22, withfirst and second thread portions of differing pitches separated by anon-threaded portion, may be internally threaded or externally threadedfor engagement with correspondingly threaded first and second members.It is also noted that the double threaded nature of the connectingelement 22, of differing pitches, provides a relatively high level ofprecision of axial movement between the first and second members (e.g.,via the combination of the thread pitches), produces an improvedmechanical advantage over other mechanisms for coupling and bringingtogether first and second members, produces a relatively high amount oftorque, the first and second members stay tightly coupled, and theconstruct remains substantially unaffected by vibration.

As shown in FIGS. 3-7 and 19 , the pre-installed threaded rod 12 of thethreaded rod assemblies 25 of the struts 110 may include a cross pin 18adjacent the strut body 5 that can be manually engaged and utilized toapply a torque to the threaded rod assemblies 25. In this way, assumingthe strut body 5 is threadably engaged with the external threads of thethreaded rod assemblies 25, the cross pin 18 can be utilized in situ toadjust the length of the struts 110, and thereby the distance andorientation between the first and second platforms 120, 130 (and,thereby, the bone or tissue segments coupled to the first and secondplatforms 120, 130).

As noted above, the strut bodies 5 of the strut assemblies 110 mayinclude a joint to the first or second platforms 120, 130 that providesfor rotation of strut bodies 5. As shown in FIGS. 14-18 , the strutbodies 5 may include a spherical projection 15 formed or coupled to anend or end portion thereof. As shown in FIG. 19 , the sphericalprojection 15 may include one or more apertures 26. The joints of thestrut bodies 5 of the strut assemblies 110 may include a first barrelknuckle 7 that includes a spherical inner cavity that is configured toaccept and mate with the spherical projection 15 of the strut bodies 5,as shown in FIG. 19 . The barrel knuckle 7 may include one or moreapertures 28 extending therethrough. The joints of the strut bodies 5may further include at least one pin 24 that is configured to extendthrough a corresponding aperture 28 of the barrel knuckle 7 and acorresponding aperture 26 of the spherical projection 15. In this way,the at least one pin 24 may limit rotation of the spherical projection15 of the strut body 5 within the barrel knuckle 7 about one axis X3-X3,as shown in FIG. 19 —thereby forming a cardan joint.

As shown in FIGS. 14-18 , the barrel knuckle 7 may also be configured toremovably and rotationally mate or attach with the first and secondplatforms 120, 130. As shown in FIGS. 15-18 , the first and secondplatforms 120, 130 may include studs 50 extending therefrom that definefree ends. The studs 50 may be arranged in closely-spaced pairs andprovided about the circumference of the first and second platforms 120,130. In some embodiments, the studs 50 may extend radially, such asperpendicular to the axis X2-X2 and/or along a plane defined by therespective platform 120, 130. As shown in FIG. 15 , the studs 50 may besubstantially cylindrical but include a flat portion 52. The flatportion 52 may be a planar chord joining two portions of the cylindricalouter surface of the studs 50. Each of the studs 50 may also include arecess or groove 52 extending at least substantially circumferentiallyabout the outer surface between the free ends thereof and the respectivefirst or second platform 120, 130. The circumferential groove 52 maythereby form a head portion of the studs 50 with a substantiallycylindrical outer surface and the flat portion 52.

As shown in FIGS. 16-18 , the barrel knuckle 7 may include an opening orcavity that is shaped and sized to receive a stud 50 of the first orsecond platform therein. As also shown in FIGS. 16-18 , the barrelknuckle 7 may include a dowel pin or other feature 1 that extends acrossa portion of the opening or cavity of the barrel knuckle 7. The openingor cavity of the barrel knuckle 7 and the dowel pin 1 may form the sameshape and configuration as the studs 50, such as the cylindrical outersurface and flat portion 52 of the studs 50 described above.

In this way, a strut 110 may be oriented such that the barrel knuckle 7and pin 1 can be aligned with and slid over the cylindrical outersurface and flat portion 52 of a stud 50, respectively, as shown inFIGS. 16 and 17 . As shown in FIG. 17 , the pin 1 may be aligned withthe groove 52 of the stud 50, and the then the strut 110 may be rotatedsuch that the pin 1 is no longer aligned with the flat portion 52 andthus trapped within the groove 52 behind the head portion of the stud50. The rotation of the strut 110 may be such that joint of the threadedrod assemblies 25 is aligned with, or at least positioned closer to, acorresponding stud 50 of the other of the first and second platforms120, 130. The joint thereby allows for at least some degree of relativerotation between the strut 110 and the respective platform 120, 130. Inthis way, the joint provides two mutually perpendicular revolute axis ofrotation between the strut 110 and the respective platform 120, 130.

In this way, the joints of the strut bodies 5 may be a revolute jointmade from features native to the platforms 120, 130 and others native tothe strut assembly 110. The joint also does not provide for a full 360degrees of rotation, but the flat portion 52 of the studs 50 may beoriented such that a range of relative rotation between the stud 50 andthe strut 110 is provided, such as the amount or range of relativerotation required or encountered during the normal course of action ofthe system 100. The joint thereby utilizes an over rotation of the strutassemblies 110 beyond their normal or expected operable range toassemble the joints. Since the strut assemblies 110 must be attached atboth ends, one end to the first platform 120 and the other end to thesecond platform 130, this joint configuration is sufficient for thefirst connection to one of the first or second platforms 120 since theremainder of the strut assembly 100 is free to swing outside of theoperable range during the attachment process.

As shown in FIG. 19 , as the studs 50 are substantially identical toeach other, the joint of the threaded rod assemblies 25 may mimic the“out of operable rotational range” feature of the joint of the strutbody 5 (or be an operationally equivalent joint). The end portion of thepre-installed threaded rod 12 of the threaded rod assemblies 25 mayinclude or form a strut screw 12 with a spherical knuckle 11 fixedthereon. The end portion of the strut screw 12 may be threaded, and adetent ring 16 and wave spring 23 may be trapped between an end cap 17threaded on to the external threads and the spherical knuckle 11. Theend cap 17 and the detent ring 16 may be rotationally coupled or fixedone another. The spherical knuckle 11 may include a series of detentsadjacent the detent ring 16, and the wave spring 23 may force the detentring 16 detents. The spherical knuckle 11 may also include at least oneaperture for the acceptance of at least one pin 24 therethrough. The atleast one pin 24 may rotationally fix the spherical knuckle 11 with acavity of a screw knuckle 15, as shown in FIG. 19 . As explained furtherbelow, the screw knuckle 15 may be coupled to a stud 50 of one of thefirst and second platforms 120, 130. As such, rotation of the threadedrod assembly 25 (e.g., via the cross pin 18) may thereby rotate thedetent ring 16 with respect to the screw knuckle 15 to provide a visualand/or tactical indication of the rotational movement and/or position ofthe threaded rod assemblies 25.

The screw knuckle 15 of the joints of the threaded rod assemblies 25 ofthe strut assemblies 110 may include a spherical inner cavity that isconfigured to accept and mate with the spherical knuckle 11 of thethreaded rod assemblies 25, as shown in FIG. 19 . As noted above, the atleast one pin 24 may extend into the screw knuckle 15 and the screwknuckle 15, which may limit rotation of the spherical knuckle 11 of thethreaded rod assemblies 25 within the screw knuckle 15 about one axisX4-X4, as shown in FIG. 19 —thereby forming a cardan joint.

As also shown in FIG. 19 , the screw knuckle 15 of the joints of thethreaded rod assemblies 25 of the strut assemblies 110 may include anopening or cavity that is shaped and sized to receive a stud 50 of thefirst or second platform 120, 130 therein. As also shown in FIG. 19 ,the screw knuckle 15 may include a pin or other feature 19. The pin 19may be provided within a groove or slot that allows the pin 19 to movebetween a position such that the pin 19 extends across a portion of theopening or cavity of the screw knuckle 15 and a position such that thepin 19 does not extend across a portion of the opening or cavity of thescrew knuckle 15.

The joints of the threaded rod assemblies 25 of the strut assemblies 110further includes a knob 20, push pin 21 and a ball 4, as shown in FIG.19 . The knob 20 may include an inner surface that forms a cam effectiveto translate the push pin 21 into and through the screw knuckle 15 andinto the pin 19. In this way, a strut 110 that is connected to one ofthe first and second platforms 120, 130 via the joint of the strut body5 may be oriented such that the screw knuckle 15 of the joint of thethreaded rod assembly 25 is aligned with and slid over the cylindricalouter surface and flat portion 52 of a stud 50. The pin 19 may bealigned with the groove 52 of the stud 50, and then the knob 20 mayrotated such that the cam of the knob 20 pushes the push pin 21 into thepin 19 such that the pin 19 extends across a portion of the opening orcavity of the screw knuckle 15 and within the groove 52 behind the headportion of the stud 50. The ball 4 may be positioned adjacent the pushpin 21 and prevent further rotation of the knob 20 from such a “locked”position. In this way, the joints of the threaded rod assemblies 25 maybe revolute joints made from features native to the platforms 120, 130and others native to the strut assembly 110.

FIGS. 20-59 illustrate another 6 DOF bone or tissue fixation systems andrelated fixation methods 200 include the desirable stability andmobility characteristics of a hexapod system without time consumingstrut-length choices and assembly difficulties. The 6 DOF bone or tissuefixation systems and related fixation methods 200 of FIGS. 20-59 aresimilar to the 6 DOF bone or tissue fixation systems and relatedfixation methods 100 of FIGS. 1-19 , and therefore like referencenumerals preceded with “2” are used to indicate like aspects orfunctions, and the description above directed to aspects or functionsthereof (and the alternative embodiments thereof) equally applies to thesystems and methods 200. As shown in FIGS. 20-44B, the system 200differs from the system 100 in that the individual strut assemblies 210(six strut assemblies 210) are coupled to each other as a single unit315 both prior to (see FIGS. 20-31 ) and after attaching to the firstand second platforms 220, 230 (see FIGS. 32-44B). As explained furtherbelow, the ends of the strut assemblies 210 include movable joints orcouplings that allow some relative movement between the pairs of strutassemblies 210, but prevent the strut assemblies 210 from becomingdisconnected from each other. In this way, the six strut assemblies 210form a single construct, unit or structure 215 “out of the box,” asshown in FIGS. 20-31 . The singular construct 215 of the six, individualbut movably coupled strut assemblies 210, as shown in FIGS. 20-31 ,allows for quick and easy manipulation and attachment to the first andsecond platforms 220, 230 as shown in FIGS. 32-44B. For example, ratherthan obtaining, assembling and/or adjusting the six strut assemblies 201individually, and then attaching them individually to each other andthen to the first and second platforms 220, 230, the singular construct215 of the six movably coupled strut assemblies 210 can be obtained andadjusted as a single unit as shown in FIGS. 20-31 , and quickly andeasily coupled to the first and second platforms 220, 230 as shown inFIGS. 32-44B.

As shown in FIGS. 45-48, 50, 58 and 59 , the singular construct 215 ofthe six strut assemblies 210 may be formed by movable joints or couplingmechanisms that couple opposing ends of adjacent strut assemblies 210.Such movable joints may be any joint that allows for movement withrespect to the first or second platforms 220, 230 to which it isattached and relative movement of the joined adjacent strut assemblies210 to allow or provide for the movement and/or angulation between thefirst or second platforms 220, 230 as shown in FIGS. 41-44B. Theexemplary movable joint shown in FIGS. 45-48, 50, 58 and 59 includes abase knuckle 201 rigidly affixed to a strut barrel 205 via a post of aknuckle pivot 204. The post of the knuckle pivot 204 may seat within acorresponding aperture in the base knuckle 201 and extend into anindentation in the strut barrel 205. In this way, the knuckle pivot 204may be rotationally coupled to the base knuckle 201 about an axis thatextends perpendicular to the strut barrel 205. As also shown in FIGS.45-48, 50, 58 and 59 , the first or primary strut screw 212 is pivotablycoupled to a pivot yoke 230A via a spring pin 213. The first strut screw212, pivot yoke 230A and spring pin 213 are configured such that thefirst strut screw 212 and pivot yoke 230A are pivotably coupled about anaxis (the spring pin 213) that extends perpendicular to the screw 212.

As shown in FIGS. 45-48, 50, 58 and 59 , the pivot yoke 230A and theknuckle pivot 204 may rotatably couple to each other via a shoulderscrew 202 that extends through apertures in shoulders of the knucklepivot 204 that are substantially aligned and spaced along the long axisof the strut barrel 205. The pivot yoke 230A may be positioned betweenthe shoulders of the knuckle pivot 204 such that it is trappedtherebetween along the long axis of the strut barrel 205, and theshoulder screw 202 may also pass through an aperture in the pivot yoke230A. In this way, the shoulder screw 202 may extend through one of theshoulders of the knuckle pivot 204, then the pivot yoke 230A, and thenultimately through the other shoulder of the knuckle pivot 204. Theknuckle pivot 204 and the pivot yoke 230A may thereby be rotatablycoupled to each other about an axis defined by the shoulder screw 202.The shoulder screw 202 may be prevented from sliding out of theapertures of the shoulders of the knuckle pivot 204 and the aperture ofthe pivot yoke 230A by a pin (not shown) that extends through the pivotyoke 230A and across at least a portion of the shoulder screw 202 withina groove or the like of the shoulder screw 202.

As shown in FIGS. 45-49 , for example, the movably joined or coupledends of the pairs or adjacent strut assemblies 210 (as explained above)may be quickly and easily affixed or coupled to the first and secondplatforms 220, 230. In this way, the singular construct 215 of the sixstrut assemblies may be quickly and easily affixed or coupled to thefirst and second platforms 220, 230. With reference to FIGS. 45-49 , forexample, the shoulder screw 202 may include a threaded portion 275 thatextends past the far shoulder of the knuckle pivot 204. In this way, inan unattached state, the threaded portion 275 of the shoulder screw 202may form free ends. The threaded portion 275 of the shoulder screws 202may thereby be aligned with a mating aperture or fixation point 270 inthe first or second platforms 220, 230 and screwed therein to couple themovable joint between the pairs of strut assemblies 210 to the first orsecond platforms 220, 230, as shown in FIGS. 47 and 48 , for example.

As shown in FIGS. 51-59 , for example, the length adjustment mechanismof the strut assemblies 210 differs from the length adjustment mechanismof the strut assemblies 110. With reference to FIGS. 51-59 , a washer208 may be seated within the base of the cavity or housing of the strutbarrel 205. As shown in FIGS. 51, 53, 56, 58 and 59 , a nut 206 may alsobe positioned within the cavity or housing of the strut barrel 205 andover the washer 208. The nut 206 may be sized smaller than the cavity ofthe strut barrel 205 such that the nut 206 is able to move radially withrespect to the long axis of the strut assembly 210 or strut barrel 205(e.g., concentric or eccentric with the cavity and/or long axis). Asshown in FIGS. 51, 53 and 56A-57B, the nut 206 may include an eccentricbore 288 and a concentric internal threaded portion 287 (or vice versa).

With reference to FIGS. 51, 53, 58 and 59 , for example, the nut 206 mayinclude radially or laterally extending grooves 280 b formed in a top orupper surface thereof. The nut 206 may also include a first dowel holeor aperture 283 extending partially through the nut 206 along the longaxis of the strut assembly 210 or strut barrel 205. The nut 206 mayfurther include a second dowel hole or aperture 284 that extends atleast partially through the nut 206 along the long axis of the strutassembly 210 or strut barrel 205. A spring 218 c and a dowel or pin 217may be positioned within the second dowel aperture 284 such that thedowel 217 is biased out of the second dowel aperture 284 and above a topsurface of the nut 206. However, the spring 218 c may include sufficienttravel that the dowel 217 can be forced further into the second dowelaperture 284 as compared to its natural or neutral position.

With further reference to FIGS. 51, 53, 58 and 59 , for example, anadjustment knob 207 may be positioned partially within the cavity orhousing of the strut barrel 205 over the nut 206. The adjustment knob207 may be rotatably coupled to the strut barrel 205 via a plurality ofpins 216 that extend radially through the strut barrel 205 and into aconcentric groove within the portion of the adjustment knob 207positioned within the strut barrel 205. In such a manner, for example,the adjustment knob 207 may be manually rotatable about the long axis ofthe strut assembly 210 or strut barrel 205. To control and/or provide anindication of the relative angular position orientation of theadjustment knob 207 with respect to the strut barrel 205, a plurality ofballs 215 may be biased by springs 218 a extending in correspondingapertures 281 within the strut barrel 205. The balls 215 may be biasedby the springs 218 a into corresponding apertures or indentations 286formed in a bottom surface of the adjustment knob 207 (see FIG. 52 ).

As shown in FIG. 52 , a bottom surface of the adjustment knob 207 mayalso include radially or laterally extending grooves 280 b thatcorrespond to the radially or laterally extending grooves 280 b in a topsurface of the nut 206. As shown in FIGS. 51, 52 and 59 , compressionsprings 218 b may be positioned between and partially within thecorresponding radially or laterally extending grooves 280 b, 280 b ofthe nut 206 and the adjustment knob 207. The compression springs 218 band the radially or laterally extending grooves 280 b, 280 b of the nut206 and the adjustment knob 207 may be configured such that the nut 206is naturally or neutrally biased eccentric to the long axis of the strutassembly 210 or strut barrel 205 within the cavity of the strut barrel205. The nut 206 may be naturally or neutrally biased such that theeccentric bore 288 of the nut is aligned (i.e., concentric) with thelong axis of the strut assembly 210 or strut barrel 205 and the first orsecond strut screw 212, 213 extending through the nut 206, as shown inFIGS. 56B and 57B. In this way, the concentric threaded portion 287 ofthe nut 206 may be natural biased away or spaced from the first orsecond strut screw 212, 213 extending through the nut 206, as shown inFIGS. 56B and 57B.

To allow for lateral or radial re-positioning of the nut 206 away fromits natural position such that the concentric threaded portion 287 ofthe nut 206 is concentric with and engages the first or second strutscrew 212, 213 as shown in FIGS. 56A and 57A, the dowels 217, 217 may beengaged within lateral or radial grooves 285 in the underside of theadjustment knob 207 as shown in FIGS. 52 and 56A-57B. When threadedportion 287 of the nut 206 is concentric with and engages the first orsecond strut screw 212, 213 as shown in FIGS. 56A and 57A, rotation ofthe adjustment knob 207 may rotate the nut 206 such that the threadedportion 287 of the nut 206 rotates with respect to the first or secondstrut screw 212, 213 to translate the strut barrel 205 (and thecomponents of the length adjustment mechanism) with respect thereto andlengthen or shorten the strut assembly 210.

As shown in FIGS. 54 and 56A-57B, the radial groove 285 of theadjustment knob 207 corresponding to the dowel 217 that is biasedaxially by the spring 218 c may include an aperture or indentation 292that accepts the corresponding dowel 217 therein. The mechanisms may beconfigured such that when the threaded portion 287 of the nut 206 isconcentric with and engages the first or second strut screw 212, 213,the aperture or indentation 292 and the corresponding dowel 217 arealigned and the spring 218 c naturally biases or positions thecorresponding dowel 217 within the aperture or indentation 292. As shownin FIGS. 54, 55 and 56A-57B, the adjustment knob 207 may include anaccess aperture that allows access to the aperture or indentation 292and, thereby, the corresponding dowel 217 to manually remove thecorresponding dowel 217 from the aperture or indentation 292 and,thereby, allow the nut 206 to be naturally biased by the compressionsprings 218 b eccentric with the first or second strut screw 212, 213with the concentric thread portion 288 spaced from the first or secondstrut screw 212, 213 (i.e., disengaged).

The length adjustment mechanism may initially be provided in the naturalstate of the nut 206 such that it biased by the compression springs 218b eccentric with the first or second strut screw 212, 213 so that theconcentric thread portion 288 is spaced from the first or second strutscrew 212, 213 (i.e., disengaged) (and the eccentric bore 287 isconcentric with the first or second strut screw 212, 213), as shown inFIGS. 56B and 57B. The strut barrel 205 may include an access aperture299 extending radially therethrough to the exterior surface of the nut206, as shown in FIGS. 55-57B and 59 . The access aperture 299 maythereby allow a member (not shown) to be inserted through the accessaperture 299 and radially or laterally translate or move the nut 206within the cavity of the strut barrel 205 and with respect to theadjustment knob 207. It is noted that the lateral or radial grooves 285in the underside of the adjustment knob 207 will allow the nut 206 anddowels 217 to radially or laterally translate or move with respect tothe adjustment knob 207. The nut 206 may be radially or laterallytranslated (via the access aperture 299) until the dowel 217 that isbiased by the spring 218 c is aligned with the aperture or indentation292 in the corresponding groove 285 of the adjustment knob 207 and thusbiased therein as shown in FIGS. 56A and 56B. In this way, the eccentricthreaded portion 288 of the nut 206 may be translated laterally orradially from out of engagement with the first or second strut screw212, 213 (as shown in FIGS. 56B and 57B) and into engagement with thefirst or second strut screw 212, 213 (as shown in FIGS. 56A and 57A) andreleasably fixed in such an arrangement. Rotation of the adjustment knob207 may thereby rotate the nut 206 such that the threaded portion 287 ofthe nut 206 rotates with respect to the first or second strut screw 212,213 to translate the strut barrel 205 (and the components of the lengthadjustment mechanism) with respect thereto to lengthen or shorten thestrut assembly 210.

FIGS. 60-87 illustrate another 6 DOF bone or tissue fixation systems andrelated fixation methods 300 include the desirable stability andmobility characteristics of a hexapod system without time consumingstrut-length choices and assembly difficulties. The 6 DOF bone or tissuefixation systems and related fixation methods 300 of FIGS. 20-59 aresimilar to the 6 DOF bone or tissue fixation systems and relatedfixation methods 100 of FIGS. 1-19 and the 6 DOF bone or tissue fixationsystems and related fixation methods 200 of FIGS. 20-59 , and thereforelike reference numerals preceded with “3” are used to indicate likeaspects or functions, and the description above directed to aspects orfunctions thereof (and the alternative embodiments thereof) equallyapplies to the systems and methods 300.

As shown in FIGS. 60-68 , the system 300 differs from the system 100 andthe system 200 in the inclusion of fiducial markers or identifiers 307as points of reference and/or measure. The fiducial markers 307 may beconfigured to assist in the identification and/or manipulation of theorientation of each strut-platform joint and the length of each strut.For example, a first platform 320 of the system 300 may be coupled to afirst bone segment and a second platform 330 of the system 300 may becoupled to a second bone segment, and then the system 300 may bemanipulated, that is, moved, such that the first bone segment and asecond bone segment are aligned in a desired position. This alignmentmay be changed over time to complete the deformity correction process.One of the bone segments may be a reference segment. The other segment,the moving segment, may be moved to align with the reference segment.The fiducial markers 307 of the system 300 may provide identification(e.g. via clinical evaluation and/or imaging) of position and/ororientation of the strut assemblies 310 as shown in FIGS. 60-68 , tofacilitate a method or process of configuring a strut to achieve aneeded or desired orientation of the bone segments. In some embodiments,the fiducial markers 307 of the system 300 may provide identification ofthe position and/or orientation of the coupling mechanisms that areprovided at the end portions of pairs of struts 310 to couple the struts310 to a respective platform 320, 330 as shown in FIGS. 60-68 , andthereby the struts 310 themselves via extrapolation, to facilitate amethod or process of configuring a strut to achieve a needed or desiredorientation of the bone segments. In this way, the markers 307 mayfacilitate a method or process of configuring struts 307 of the system300 to achieve a needed or desired orientation of the bone segments,such as a method or process disclosed in U.S. Pat. No. 8,419,732, whichis expressly incorporated herein in its entirety. In some embodiments,the method or process may utilize the markers 307 to determine a“current” position and/or orientation of the struts 307 and a“corrected” position and/or orientation of the struts. In someembodiments, the method or process may determine the how the markers 307(and thereby the corresponding struts 310 should be positioned and/ororiented in situ.

As shown in FIGS. 60-71 and 75-78 , the markers 307 may be sphericalknobs or heads of a shoulder screw 302 that couples an attachment base303 that couples a pair of adjacent strut assemblies 310 to a respectiveplatform 320, 330. In this way, the markers 307 may be utilized totorque the shoulder screw 302 to threadably removably couple theattachment base 303 (and thereby the strut assemblies 310 coupledthereto) to a respective platform 320, 330, as explained further below.The markers 307 may be positioned on the exterior of the system 300,such as past an outer end of a respective platform 320, 330. The markers307 may be configured to visually appear when imaged, such as whenx-rayed. The markers 307 may include at least one marker that isvisually different in some than the other markers 307. For example, asshown in FIGS. 60-71 and 75-78 the markers 307 include a uniquerelatively smaller spherical marker at one end of the system 300 in alocation or position on the respective platform 320, 330. The uniquemarker 307 may be used as a reference marker 307 to determine theorientation and position of the system 300 and the strut assemblies 310,such as by the method described above. Further, such a unique marker 307may be utilized as a reference to effectuate the positions and/ororientations determined by the aforementioned method.

As shown in FIGS. 60-71 and 75-78 , the markers 307 may be sphericalknobs or heads of a shoulder screw 302 that removably fix an attachmentbase 303, to which a pair of adjacent strut assemblies 310 are movablycoupled, to a respective platform 320, 330. The markers 307 may therebybe positioned on the exterior of the construct 315 and clearly visiblein profile. Further, the markers 307 may be manually engageable tomanually screw the shoulder screws 302 into their respective platform320, 330.

The markers 307 may also initially be utilized to unpack or ready thesystem 300 by removing the shoulder screws 302 to separate the construct315 from end plates 371 and a connecting rod 373 extending therebetween,as shown in FIGS. 60-64 . Each end plate 371 may be coupled to threebase plates 303 at an end of the construct 315 with each base plate 303coupled to a pair of strut assemblies 310. As shown in FIGS. 60-64 , theshoulder screws 302 may each threadably couple through a respective slotor aperture in an end plate 371 and into a respective base plate 303 toclamp the end plate 371 between a collar or shoulder 377 and/or themarker 307 of the shoulder screws 302 and the respective base plates303. The connecting rod 373 may threadably couple to, and extendbetween, the base plates 371. The end plates 371 and the connecting rod373 may thereby fix the base plate 303, and thereby the strut assemblies310, together and prevent the strut assemblies 310 from extending andretracting.

As shown in FIGS. 66-81 , opposing ends of a pair of adjacent strutassemblies 310 may be movably coupled to substantially opposing lateralsides of a corresponding base plate 303. Each strut assembly 310 may berotatably coupled to a side of a corresponding base plate 303 such thatthe strut assembly 310 is rotatable about at least two axis, as shown inFIGS. 66-81 . The base plate 303 may be triangular in shape with curvedouter lateral surfaces. The base plate 303 may include an outerlongitudinal engagement surface 391 and an inner longitudinal engagementsurface 393, as shown in FIGS. 66-81 . The outer longitudinal engagementsurface 391 and/or an inner longitudinal engagement surface 393 may beplanar and/or configured to mate with corresponding surfaces of studs 50projecting radially from the platform 320, 330, as shown in FIGS. 67-76. The studs 50 may also inner and outer surfaces corresponding to theengagement surfaces 391, 393 of the base plates 303 so that the baseplates 303 may be coupled to and abut either the inner or outercorresponding surfaces of the studs 50, as shown in FIGS. 67-76 .Further, as shown in FIGS. 67, 68 and 76 , the base plates 303 may bepositioned between and coupled to a pair of platforms 320, 330 such thatboth the inner and outer engagement surfaces 391, 393 of the base plates303 engages a corresponding portion of the studs 50 of the pair ofplatforms 320, 330.

As also shown in FIGS. 66-81 , the base plates 303 may also include aprojection 395 extending from the inner and/or outer engagement surfaces391, 393. The projection 395 may be position on a laterally and/orradially outward portion of the engagement surfaces 391, 393. Theprojections 395 may be configured to mate within a correspondingaperture, slot, recess or the like in the studs 50 of the platforms 320,330, as shown in FIGS. 67-76 . The slot of the platforms 320, 330 may beopen at the outer lateral and/or radial end of the studs 350 to allowthe projection 395 to be translated or slid therein. In addition to theslot corresponding to the projections 395 of the base plates 303, thestuds 350 of the platforms 320, 330 may also include and aperture orportion extending from the slot (or separated from) configured to allowa shoulder screw 302 to threadably engage and extend therethrough, asshown in FIGS. 66-81 . The base plates 303 may also include and apertureconfigured to threadably engage with the shoulder screw 302. In thisway, a projection 395 may be positioned within a corresponding slot of astud 350, an engagement surface 391, 393 of the corresponding base plate303 may engage or abut a corresponding surface of the stud 350, andshoulder screw 302 may threadably engage and extend into the stud 350and the base plate 303 to rigidly removably couple the base plate 303(and the strut assemblies 310 coupled thereto) and the correspondingplatform(s) 320, 330, as shown FIGS. 67-76 . In some embodiments, theaperture or slot of the studs 350 of the platforms 320, 330 that allowthe shoulder screws 302 to pass therethrough may include a bevel orcountersink extending thereabout into the inner and/or outer engagementsurfaces 391, 393 to accept a corresponding collar or shoulder 377 ofthe shoulder screws 302 therein, as shown FIGS. 67-76 . The countersinkand the corresponding collar 377 may aid in fixedly or rigidly couplingthe base plates 303 (and the strut assemblies 310 coupled thereto) andthe corresponding platform(s) 320, 330.

As shown in FIGS. 82-92 , the system 300 also differs from the system100 and the system 200 in the configuration of the length adjustmentmechanisms of the strut assemblies 310 that are configured toselectively vary the arrangement of the strut barrel 305 and first orsecond threaded rod 312, 313. As shown in FIGS. 82-92 , the strut barrel305 includes a head portion at the free end thereof that includes outerthreads 313 and a cavity 309. The head portions of the strut barrel 305also includes a plurality of the apertures extending from the outerthreads 313 to the cavity 309. In some embodiments, at least threeapertures are provided and may be radially extending and evenlycircumferentially spaced. As also shown in FIGS. 82-92 , a ball bearingor other member may be carried, housed or otherwise positioned at leastpartially within the apertures of the head portion of the strut barrel305. In this way, the ball bearing or other members may be able to moveat least partially into, or at least partially out of, the cavity 309 todiffering degrees.

The length adjustment mechanisms of the strut assemblies 310 may furtherinclude a adjust nut 306 with a bore that includes a threaded portion387 and a non-threaded portion 387′, as shown in FIGS. 88, 89 and 92 .The adjust nut 306 and the cavity 309 may be configured such that theadjust nut 306 can be positioned or housed within the cavity 309 withadditional space or a portion of the cavity 309, as shown in FIG. 92 .Stated differently, the cavity 309 may be larger than the adjust nut 306such that the adjust nut 306 may be able to translate within the cavity309, as shown in FIG. 92 . The length adjustment mechanisms of the strutassemblies 310 may also include a release nut 398 that is threadablyengaged with the external threads 313 of the head portion of the strutbarrel 305. The release nut 398 may include an inner threaded surfacewith a groove or recess therein, as shown in FIGS. 89 and 92 .

The groove and threaded portions of the inner surface of the release nut398 may thereby move the ball bearings or other members in/out of thecavity 309 of the head portion of the strut barrel 305, as shown in FIG.92 . In this way, the release nut 398 may be adjusted to either push theball bearings or other members at least partially into the cavity 309via the threaded portions as shown in FIG. 92 , or to a positioned suchthat the inner groove is aligned with the ball bearings or other membersto allow the ball bearings or other members to move therefrom and atleast partially out of the cavity 309. The adjust nut 306 positionedwithin the cavity 309 may thereby be biased by the ball bearings orother members to a position concentric with the threaded rod 312, 313extending through the strut barrel 305, or allow the adjust nut 306 moveto a position eccentric with the threaded rod 312, 313. In theconcentric arrangement of the adjust nut 306 and the threaded rod 312,313, the threaded portion 387 of the adjust nut 306 may be engaged withthe threads of the threaded rod 312, 313, and in the eccentric positionof the adjust nut 306 the threaded portion 387 of the adjust nut 306 maybe disengaged with the threads of the threaded rod 312, 313 and thenon-threaded portion 387′ may engaged with the threads of the threadedrod 312, 313. It is noted that when the release nut 398 is position toallow the adjust nut 306 to move within the laterally cavity 309, theforce between the threads of the threaded portion 387 and the threadedrod 312, 313 may act to move the release nut 398 into the eccentricposition. In such a state, the non-threaded portion 387′ may engagedwith the threads of the threaded rod 312, 313 (if any portion of theadjust nut 306 engages therewith) to allow the threaded rod 312, 313 tofreely axially or longitudinally translate through the strut barrel 305.

As shown in FIGS. 82-92 , the length adjustment mechanisms of the strutassemblies 310 may also include an adjustment knob 307 with lower neckregion that is configured to be positioned within the cavity 309 abovethe adjust nut 306. The lower neck region of the adjustment knob 307 andan upper portion of the cavity 309 may include grooves, races orchannels to capture a plurality of ball bearings or any other rotationalproviding members therebetween, as shown in FIGS. 88-92 . The adjustmentknob 307 may also include a threaded longitudinally extending aperture391 that extends to the top or upper rim of the head portion of thestrut barrel 305. As shown in FIGS. 88-92 , the top or upper rim of thehead portion of the strut barrel 305 may include circumferentiallyspaced indentations, and a spring plunger 399 or other member threadablyengaged within the aperture 391 such that the plunger 399 engages theindentations when aligned therewith. The plunger 399 and theindentations may thereby provide a tactile indication of the rotationalposition of the adjustment knob 307 with respect to the strut barrel305.

The lower end or portion of the adjustment knob 307 may also include atleast one slot 331 (or projection) extending at least partially acrossthe cavity 309, as shown in FIG. 90 . Similarly, the upper end orportion of the adjust nut 306 may include at least one projection 333(or slot) extending at least partially across the cavity 309 andconfigured to mate with the slot 331 of the adjustment knob 307, asshown in FIG. 90 . The slot 331 of the adjustment knob 307 and theprojection 333 of the adjust nut 306 may thereby mate such that rotationof the adjustment knob 307 effectuates rotation of the adjust nut 306.In this way, a user may rotate the adjustment knob 307 to rotate theadjust nut 306 within the cavity 309 of the head portion of the of thestrut barrel 305. As discussed above, the user may also rotate therelease nut 398 to adjust its longitudinally or axial position totranslate the ball bearings with respect to the cavity 309 to force thenut to be concentric with the threaded rod 312/313 to engage thethreaded portion 287 therewith. In such an arrangement, the adjustmentknob 307 can be rotated to rotate the nut 398 and force the threaded rod312/313 through the strut barrel 305 to lengthen or shorten the strutassembly 310, depending upon the direction of rotation. The adjustmentknob 307 may thereby be utilized for fine length adjustment of the strutassembly 310. For gross adjustment of the length of a strut assembly310, the user may rotate the release nut 398 to adjust itslongitudinally or axial position to align the groove with the ballbearings to allow the ball bearing to move away from the cavity 309 and,thereby, allow the adjust nut 306 to move eccentric with the threadedrod 312/313. As noted above, in the eccentric position of the adjust nut306, the threaded portion is not in engagement with the threaded rod312/313 to allow the threaded rod 312, 313 to freely axially orlongitudinally translate through the strut barrel 305.

FIGS. 82-105 illustrate additional 6 DOF bone or tissue externalfixation systems and related fixation methods 400 that include thedesirable stability and mobility characteristics of a hexapod systemwithout time consuming strut-length choices and assembly difficulties.The external bone or tissue fixation systems and related fixationmethods 400 of FIGS. 82-105 are similar to the external fixation systemsand related fixation methods 100 of FIGS. 1-19 , the external fixationsystems and related fixation methods 200 of FIGS. 20-59 , and theexternal fixation systems and related fixation methods 300 of FIGS.20-59 , and therefore like reference numerals preceded with “4” are usedto indicate like aspects or functions, and the description abovedirected to aspects or functions thereof (and the alternativeembodiments thereof) equally applies to the external fixation systemsand methods 400.

As shown in FIGS. 82-105 , the exemplary system 400 differs from thesystem 100, the system 200 and the system 300 in the rotatable couplingor connection mechanism between the strut assemblies 410 (e.g., pairs ofoppositely oriented or extending strut assemblies) and the platforms orrings 420, 430. As shown in FIGS. 82-85 the system 400 utilizes strutmounts 441 that securely and removably couple and clamp to correspondingprojections 443 of the platforms 420, 430 as shown in FIGS. 84 and 86-89. The mounts 441 may be configured to couple to the platforms 420, 430by clamping onto the projections 443 via a threaded post portion 402that threadably engages within a threaded aperture 447 positionedadjacent to the projections 443. In some embodiments, only the apertures447 of the platforms 420, 430 that are positioned adjacent or immediatebehind the projections 443 may be threaded (i.e., and other similarapertures of the platforms 420, 430 may be non-threaded).

The threaded post 402 may extend through the threaded aperture 447 ofthe platforms 420, 430 so that a portion of the post 402 extendsoutwardly past the platforms 420, 430 on an opposing side thereof ascompared to the mount 441, as shown in FIGS. 84 and 85 . In someembodiments, this extended portion of the threaded post 402 may beutilized to couple other mechanisms to the platforms 420, 430. Thethreaded posts 402 may be manually threadably engaged to the threadedapertures 447 of the platforms 420, 430 via the fiducial markers 407positioned at, or extending from, an end of the post portion 402. Forexample, the fiducial markers 407 may be manually engaged by a surgeonor other user and utilized to rotate the threaded posts 402 such thatthe threaded posts 402 threadably engage and tighten down into thethreaded apertures 447. Similarly, the fiducial markers 407 may beutilized to rotate the threaded posts 402 out from threaded aperture447. In some embodiments, the fiducial markers 407 may include anaperture or indentation configured to allow a tool to apply a torque tothe fiducial markers 407 to effectuate rotation of the threaded posts402 relative to the threaded apertures 447.

As shown in FIG. 82 , the mount 441 may be configured such that thefiducial markers 407 are positioned interiorly of the platforms 420, 430such that the posts 402 extend through the threaded apertures 447 froman interior side thereof to an exterior side thereof at least generallyalong the longitudinal axis of the strut assemblies 410. In this way,the fiducial markers 407 may be spaced from the ends of the strutassemblies 410 and not interfere with the extended nature of thethreaded rod portion 412, 413 of the strut assemblies 410 extending outfrom the strut barrels 405. The outer portions of the platforms 420,430, particularly adjacent to the projections 443, may thereby be openand void of any structure that may interfere with the threaded rodportion 412, 413 of the strut assemblies 410 extending out from thestrut barrels 405 past the platforms 420, 430.

As shown in FIGS. 86-89 , each of the platforms 420, 430 may include atleast three projections 443 (to couple to a pair of strut assemblies410, such as three pairs of strut assemblies 410 in a hexapodconfiguration) that extend radially outward from the platforms 420, 430.Each projection 443 may include a substantially flat or planarouter-most face in the radial direction, as shown in FIGS. 86-89 . Asalso shown in FIGS. 86-89 , each projection 443 may include angledsupport surface 449 that extend from the planar outer face and the innerand outer surfaces 451 of the platforms 420, 430. The planar outer facesof the projections 443 may thereby be thinner than the main portions ofthe platforms 420, 430 as measured between the inner and outer surfaces451. The planar outer face of the projections 443 may be orientedsubstantially perpendicular to the inner and outer surfaces 451 of theplatforms 420, 430. The angled support surfaces 449 of the projections443 may thereby face or be angled radially outward and either outwardlyor inwardly (e.g., the support surface 449 extending between the outerface of the projection 443 and the outer surface 451 of the platforms420, 430 may face radially outward and upward, and the support surface449 extending between the outer face of the projection 443 and the innersurface 451 of the platforms 420, 430 may face radially outward andinward). As the mounts 441 may be positioned on the inward facessurfaces 451 of the platforms 420, 430, as shown in FIG. 82 , the mounts441 may engage the inwardly-facing support surfaces 449 of theprojection 443 and the inward faces surfaces 451 of the platforms 420,430 to securely clamp to the platforms 420, 430, as explained furtherbelow.

As shown in FIGS. 90-83 , the mounts 441 may clamp or couple to theplatforms 420, 430 (e.g., via the projections 443 and threaded apertures447) such that a back portion of the mounts 441 extends radially outwardpast the outer face of the projections 443 and the outward surface ofthe platforms 420, 430. This back portion of the mounts 441 may includea pair of trunnions 453 rotatably coupled within apertures or a channelof the mounts 441, as shown in FIGS. 90-98 . The trunnions 453 mayextend outwardly from a respective mount 441 to allow one end portion ofthe first threaded rod 412 or a strut barrel 405 to be rotatably coupledthereto, as shown in FIGS. 82-85 . For example, a first threaded rod 412and a strut barrel 405 may be rotatably coupled to the exposed portionsof a pair of trunnions 453 of a mount 441, such as via a pin connection.The connection between the trunnions 453 and the pair of strutassemblies 410 of each mount 441 may provide relative rotation of thestrut assemblies 110 about an orthogonal axis.

The trunnions 453 themselves may also provide relative rotation of thestrut assemblies 110 about an orthogonal axis. For example, thetrunnions 453 may be able to rotate within the aperture(s) or channel(s)of the mount 441. In some embodiments, the mount 441 may be configuredto provide a limited amount of rotation of the trunnions 453 withrespect to the mount 441 (e.g., such as about 300 degrees or 270degrees). In some embodiments, the trunnions 453 may be cylindricalmembers contained within a cylindrical bore or aperture of the mount441, as shown in FIGS. 90-98, 101 and 105 . As shown in FIGS. 97 and 98, the portion of the trunnions 453 positioned within the mount 441 mayinclude a groove that partially encircles or extends about the outersurface thereof. As shown in FIGS. 90, 91, 93, 94 and 96-98 , the mount441 may include trunnion pins or other mechanism, such as spring pins,that extend through respective apertures such that the pins mate withinthe grooves of the trunnions 453 (see FIGS. 97 and 98 ). The trunnionpins thereby prevent the trunnions 453 from disengaging from the mounts441 and allow limited rotation of the trunnions 453 within the mount441. In some other embodiments, the grooves may encircle the trunnions453 such that they are able to fully or completely rotate within themounts 441. To allow free and smooth rotation of the trunnions 453within the mount 441, the mount 441 may include an o-ring, washer orother similar member 457 positioned between the pair of trunnions 453,as shown in FIG. 98 .

The threaded post 402 may be movably retained or captured within akeyhole aperture 477 of the mount 441 via a post pin or other member457, such as a spring pin, as shown in FIGS. 90, 93-103 . As shown inFIGS. 93, 97, 98 and 103 , the mount 441 may include a keyhole or otherirregular-shaped aperture 477 extending therethrough between an exteriorsurface and an engagement surface 467. The engagement surface 467 of themount 441 may engage the interior surface of the platforms 420, 430during use, as shown in FIG. 93 . As shown in FIGS. 93 and 97 , the post402 may include a threaded portion 465, a conical or beveled flange 459,and a non-threaded portion 463 extending between the threaded portion465 and the beveled flange 459. The non-threaded portion 463 of the post402 may define a smaller diameter or width than the threaded portion 465and the beveled flange 459. The irregular-shaped aperture 477 mayinclude a first portion that is sized to allow the threaded portion 465to pass therethrough, and a second portion that is sized to prevent thethreaded portion 465 to pass therethrough but allow the non-threadedportion 463 to pass therethrough or be seated therein, as shown in FIG.98 . To capture the post 402 within the irregular-shaped aperture 477and movably couple the post 402 to the mount 441, the post pin 457 maypass at least partially through the first portion of irregular-shapedaperture 477 with the non-threaded portion 463 positioned thereon to atleast partially block off the first portion. As the second portion ofthe irregular-shaped aperture 477 is too small for the threaded portion465 and the beveled flange 459 to pass through, the post 402 iseffectively captured within the irregular-shaped aperture 477. The mount441 may thereby include an aperture or channel configured to positionthe post pin 457 at least partially through the first portion ofirregular-shaped aperture 477. In use, the mounts 443 may pre-assembledwith the posts 402 captured within the mounts 443 via the post pins 457.

The outer surface of the mount 441 that opposes the engagement surface467 may include a bevel or countersink about a portion of theirregular-shaped aperture 477 corresponding to the conical or beveledflange 459, as shown in FIGS. 93, 97, 99, 102 and 103 . The countersinkof the irregular-shaped aperture 477 may be positioned at leastpartially within or about the second smaller portion of theirregular-shaped aperture 477. In this way, when the threaded portion465 of the post 402 is torqued down into the threaded aperture 447 ofthe platform 420, 430, the engagement surface 467 abuts and engages theinner surface 451 of the platform 420, 430 and the beveled flange 459self-seats or centers itself into the countersink portion of theirregular-shaped aperture 477, as shown in FIGS. 90, 92-95, 97 and 98 .

The countersink of the irregular-shaped aperture 477 may also beconfigured to pull or translate the mount 441 radially inwardly suchthat a lip or arm portion 445 of the mount 441 engages the inner angledsupport surface 449 of the projection 443 of the platform 420, 430, asshown in FIGS. 84, 93 and 97 . As shown in FIGS. 84, 93, 94, 95, 97, 99,101 and 105 , the lip or arm portion 445 of the mounts 443 may extendaxially inwardly from the engagement surface 467 and radially inwardlytoward the interior or center of the platform 420, 430. The lip portion445 of the mounts 443 may thereby extend along or about the planar outerface of the projection 443 and the inward angled support face 449, asshown in FIGS. 84 and 93 . Further, the mount 441 and projection 443 maybe configured such that when the threaded portion 465 of the post 402 istorqued down into the threaded aperture 447 of the platform 420, 430,and the engagement surface 467 abuts and engages the inner surface 451of the platform 420, 430 and the beveled flange 459 seats itself intothe countersink portion of the irregular-shaped aperture 477 therebytranslating the mount 441 radially inwardly, the lip portion 445 engagesthe inner angled support surface 449 of the projection 443 of theplatform 420, 430. In this way, the mount 441 may be clamped to theinner surface 451 and the inner angled support surface 449 of a platform420, 430 to securely couple thereto. It is noted that the other portionsof the lip portion 445 may be spaced slightly from the planar outersurface and the outer angled support surface 449 of the projections 443when the mount 441 is clamped to the platforms 420, 430, as shown inFIG. 93 .

In use, the threaded portion 465 of the post 402 may threaded into thethreaded aperture 447 associated with one of the projections 443 of oneof the platforms 420, 430. The non-threaded portion 463 of the post 402may be positioned within the second larger portion of theirregular-shaped aperture 477 to allow the lip portion 445 to extendpast the outer surface and angles support surfaces 449 of the projection443. As the post is torqued and tightened into the threaded aperture447, the beveled flange portion 459 may engage the countersink of theirregular-shaped aperture 477 and seat itself thereon by translating themount 441 radially inwardly (and the non-threaded portion 463 translatetoward or partially into the first smaller portion of theirregular-shaped aperture 477). The engagement surface 467 of the mount441 may thereby be forced against and engage and abut the inward supportor engagement surface 451 of the platform 420, 430. Such radially inwardmotion or translation of the mount 441 may thereby the lip portion 445of the mount 441 against and into engagement or abutment with the innerangled support surface 449 of the projection 443. In this way, the mount441 (and thereby the strut assemblies coupled thereto) may be clamped tothe angled support surface 449 of the projection 443, the inward supportor engagement surface 451 of the platform 420, 430 and the threadedaperture 447 of the platform 420, 430.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Numerous changes and modificationsmay be made herein by one of ordinary skill in the art without departingfrom the general spirit and scope of the invention as defined by thefollowing claims and the equivalents thereof. For example, theabove-described embodiments (and/or aspects thereof) may be used incombination with each other. In addition, many modifications may be madeto adapt a particular situation or material to the teachings of thevarious embodiments without departing from their scope. While thedimensions and types of materials described herein are intended todefine the parameters of the various embodiments, they are by no meanslimiting and are merely exemplary. Many other embodiments will beapparent to those of skill in the art upon reviewing the abovedescription. The scope of the various embodiments should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled. In the appendedclaims, the terms “including” and “in which” are used as theplain-English equivalents of the respective terms “comprising” and“wherein.” Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects. Also, theterm “operably connected” is used herein to refer to both connectionsresulting from separate, distinct components being directly orindirectly coupled and components being integrally formed (i.e.,monolithic). Further, the limitations of the following claims are notwritten in means-plus-function format and are not intended to beinterpreted based on 35 U.S.C. § 112, sixth paragraph, unless and untilsuch claim limitations expressly use the phrase “means for” followed bya statement of function void of further structure. It is to beunderstood that not necessarily all such objects or advantages describedabove may be achieved in accordance with any particular embodiment.Thus, for example, those skilled in the art will recognize that thesystems and techniques described herein may be embodied or carried outin a manner that achieves or optimizes one advantage or group ofadvantages as taught herein without necessarily achieving other objectsor advantages as may be taught or suggested herein.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the disclosuremay include only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

I claim:
 1. A strut assembly for an external fixation system, comprising: a strut body comprising an internal cavity, an internally threaded adjuster and a first axial end portion that comprises at least one first joint member configured to movably couple the strut body and a first external fixation platform together; an externally threaded first rod extending axially within the internal cavity of the strut body and operably threadably coupled with the adjuster, the first rod comprising a second axial end portion with at least one second joint member configured to movably couple the first rod and a second external fixation platform together, wherein the first rod axially extends from within the internal cavity, past a second axial end portion of the strut body, and to the at least one second joint member; and at least one externally threaded second rod comprising a fourth end portion that is configured to couple with a third axial end portion of the first rod such that the first and second rods extend coaxially, wherein an axial length of the strut assembly extending between the first axial end portion of the strut body and the second axial end portion of the first rod is adjustable via rotation of the adjuster, and wherein the strut body and the first rod are configured such that the second rod is attachable to the first rod while the strut body and the first external fixation platform remain coupled together via the at least one first joint member, while the first rod and the second external fixation platform remain coupled together via the at least one second joint member, and while the first rod remains operably coupled with the adjuster.
 2. The strut assembly of claim 1, wherein the adjuster is rotationally coupled and axially fixed to the strut body.
 3. The strut assembly of claim 2, wherein the adjuster is partially threaded, and wherein the threaded portion of the adjuster is biased into engagement with the first rod via a release nut threaded engaged with external threads of the strut body.
 4. The strut assembly of claim 3, wherein translation of the release nut along the strut body in a first direction forces the nut concentric with the first rod and into threaded engagement therewith.
 5. The strut assembly of claim 4, wherein translation of the release nut along the strut body in a second direction allows the release nut to translate eccentric to the first rod and disengage therewith.
 6. The strut assembly of claim 1, wherein the at least one first joint member and the at least one second joint member each comprise a respective mount that is configured to fixedly couple with the first and second platforms, respectively, via projections and apertures of the first and second platforms.
 7. The strut assembly of claim 6, wherein each mount includes a threaded post that is configured to extend through the apertures of the first and second platforms.
 8. The strut assembly of claim 7, wherein a fiducial marker is positioned at an end of each threaded post.
 9. The strut assembly of claim 7, wherein each projection includes an angled support surface and inner support surface, and wherein each mount includes an engagement surface that engages the inner support surface and a lip portion that engages the angled support surface to clamp the mount to the first or second platform.
 10. The strut assembly of claim 9, wherein each threaded post passes through an irregular aperture of a respective mount, and wherein a portion of the irregular aperture includes a countersink.
 11. The strut assembly of claim 10, wherein each threaded post includes a beveled flange configured to mate with the countersink of the associated irregular aperture, and wherein the beveled flange acts to translate the mount with respect to the first or second platform so that the lip portion engages the angled support surface.
 12. The strut assembly of claim 1, wherein the third axial end portion of the first rod comprises a first internally threaded opening extending from a first end of the first rod, the first internally threaded opening defining a first thread pitch.
 13. The strut assembly of claim 12, wherein the fourth axial end portion of the second rod comprises a second internally threaded opening extending from a second end of the second rod, the second internally threaded opening defining a second thread pitch that is smaller than the first thread pitch.
 14. The strut assembly of claim 13, further comprising a connecting element comprising a first externally threaded portion of the first thread pitch, a second externally threaded portion of the second pitch, and a non-threaded portion positioned axially between the first and second externally threaded portions.
 15. The strut assembly of claim 14, wherein the first externally threaded portion of the connecting element is configured to threadably engage and axially translate within the first internally threaded opening, and the second externally threaded portion of the connecting element is configured to threadably engage and axially translate within the second internally threaded opening.
 16. The strut assembly of claim 15, wherein rotation and axial translation of the first externally threaded portion of the connecting element within the first internally threaded opening, and the second externally threaded portion of the connecting element within the second internally threaded opening, causes the first rod and the second rod to be axially drawn together until end surfaces of first end and the second end abut.
 17. The strut assembly of claim 16, wherein the second rod and the connecting element are configured such that initial rotation of connecting element rotates the connecting element and the second rod with respect to first rod such that the second externally threaded portion of the connecting element advances into the first internally threaded opening.
 18. The strut assembly of claim 16, wherein the first end and the second end each include at least one keying element that extends axially toward each other, the keying elements include mating faces that are configured to become engaged with each other when the first rod and the second rod are axially drawn together to a first extent via the connecting element.
 19. The strut assembly of claim 18, wherein the mating faces are configured to prevent relative rotation and allow axial translation between the first rod and the second rod as the connecting element is rotated and advanced into the first internally threaded opening.
 20. The strut assembly of claim 19, wherein the keying elements comprise projections that extend axially past the end surfaces of first end and the second end, and wherein the first end and second end include recesses configured to contain the keying element associated with the other of the first end or second end when the first end and second end abut.
 21. The strut assembly of claim 16, wherein, when the first end and second end abut, external threads of the first rod and the second rod cooperatively form a uniform and clocked thread pitch.
 22. The strut assembly of claim 16, wherein the second rod further comprises a third internal opening extending from a third end thereof that opposes the second end thereof, the third internal opening being in communication with the second internally threaded opening such that the connecting element is accessible from the third end.
 23. The strut assembly of claim 22, wherein the third internal opening comprises internal threads of the first thread pitch extending from the third end.
 24. The strut assembly of claim 16, wherein rotation and axial translation of the first externally threaded portion of the connecting element within the first internally threaded opening, and the second externally threaded portion of the connecting element within the second internally threaded opening, causes the connecting element to advance into the first internally threaded opening to a greater extent than the connecting element is advanced through the second externally threaded portion.
 25. The strut assembly of claim 16, wherein first and second rods and the connecting element are configured such that when the end surfaces of first end and second end abut, the non-threaded portion of the connecting element extends within the first and second internally threaded openings.
 26. The strut assembly of claim 1, wherein the first and second rods are configured such that when the third axial end portion of the first rod and the fourth end portion of the second rod are coupled, the first and second rods form a clocked consistent external thread profile.
 27. An external bone and/or tissue fixation system, comprising: a first platform configured to couple to a first bone and/or tissue segment; a second platform configured to couple to a first bone and/or tissue segment; and a plurality of length-adjustable struts coupled between the first and second platforms, wherein at least one of the plurality of length-adjustable struts comprises a first strut comprising: a strut body comprising an internal cavity, an internally threaded adjuster and a first axial end portion that comprises at least one first joint member configured to movably couple the strut body and a first external fixation platform together; an externally threaded first rod extending axially within the internal cavity of the strut body and operably threadably coupled with the adjuster, the first rod comprising a second axial end portion with at least one second joint member configured to movably couple the first rod and a second external fixation platform together, wherein the first rod axially extends from within the internal cavity, past a second axial end portion of the strut body, and to the at least one second joint member; and at least one externally threaded second rod comprising a fourth end portion that is configured to couple with a third axial end portion of the first rod such that the first and second rods extend coaxially, wherein an axial length of the strut assembly extending between the first axial end portion of the strut body and the second axial end portion of the first rod is adjustable via rotation of the adjuster, and wherein the strut body and the first rod are configured such that the second rod is attachable to the first rod while the strut body and the first external fixation platform remain coupled together via the at least one first joint member, while the first rod and the second external fixation platform remain coupled together via the at least one second joint member, and while the first rod remains operably coupled with the adjuster.
 28. The fixation system of claim 27, wherein each of the plurality of length-adjustable struts comprises the first strut.
 29. The fixation system of claim 28, wherein the plurality of length-adjustable struts are coupled to each other and form a singular construct prior to coupling to the first and second platforms.
 30. The fixation system of claim 28, wherein the strut assemblies are coupled to the first and second platforms in pairs of strut assemblies spaced about the first and second platforms. 